// See License comments in shader string

(function(Blotter, _) {

  Blotter.Assets.Shaders.Noise2D = [
    "//",
    "// Description : Array and textureless GLSL 2D simplex noise function.",
    "//      Author : Ian McEwan, Ashima Arts.",
    "//  Maintainer : ijm",
    "//     Lastmod : 20110822 (ijm)",
    "//     License : Copyright (C) 2011 Ashima Arts. All rights reserved.",
    "//               Distributed under the MIT License. See LICENSE file.",
    "//               https://github.com/ashima/webgl-noise",
    "//",
    "",
    "vec2 n2mod289(vec2 x) {",
    "  return x - floor(x * (1.0 / 289.0)) * 289.0;",
    "}",
    "",
    "vec3 n2mod289(vec3 x) {",
    "  return x - floor(x * (1.0 / 289.0)) * 289.0;",
    "}",
    "",
    "vec4 n2mod289(vec4 x) {",
    "  return x - floor(x * (1.0 / 289.0)) * 289.0;",
    "}",
    "",
    "vec3 permute(vec3 x) {",
    "  return n2mod289(((x*34.0)+1.0)*x);",
    "}",
    "",
    "float snoise(vec2 v)",
    "  {",
    "  const vec4 C = vec4(0.211324865405187,  // (3.0-sqrt(3.0))/6.0",
    "                      0.366025403784439,  // 0.5*(sqrt(3.0)-1.0)",
    "                     -0.577350269189626,  // -1.0 + 2.0 * C.x",
    "                      0.024390243902439); // 1.0 / 41.0",
    "// First corner",
    "  vec2 i  = floor(v + dot(v, C.yy) );",
    "  vec2 x0 = v -   i + dot(i, C.xx);",
    "",
    "// Other corners",
    "  vec2 i1;",
    "  //i1.x = step( x0.y, x0.x ); // x0.x > x0.y ? 1.0 : 0.0",
    "  //i1.y = 1.0 - i1.x;",
    "  i1 = (x0.x > x0.y) ? vec2(1.0, 0.0) : vec2(0.0, 1.0);",
    "  // x0 = x0 - 0.0 + 0.0 * C.xx ;",
    "  // x1 = x0 - i1 + 1.0 * C.xx ;",
    "  // x2 = x0 - 1.0 + 2.0 * C.xx ;",
    "  vec4 x12 = x0.xyxy + C.xxzz;",
    "  x12.xy -= i1;",
    "",
    "// Permutations",
    "  i = n2mod289(i); // Avoid truncation effects in permutation",
    "  vec3 p = permute( permute( i.y + vec3(0.0, i1.y, 1.0 ))",
    "   + i.x + vec3(0.0, i1.x, 1.0 ));",
    "",
    "  vec3 m = max(0.5 - vec3(dot(x0,x0), dot(x12.xy,x12.xy), dot(x12.zw,x12.zw)), 0.0);",
    "  m = m*m ;",
    "  m = m*m ;",
    "",
    "// Gradients: 41 points uniformly over a line, mapped onto a diamond.",
    "// The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)",
    "",
    "  vec3 x = 2.0 * fract(p * C.www) - 1.0;",
    "  vec3 h = abs(x) - 0.5;",
    "  vec3 ox = floor(x + 0.5);",
    "  vec3 a0 = x - ox;",
    "",
    "// Normalise gradients implicitly by scaling m",
    "// Approximation of: m *= inversesqrt( a0*a0 + h*h );",
    "  m *= 1.79284291400159 - 0.85373472095314 * ( a0*a0 + h*h );",
    "",
    "// Compute final noise value at P",
    "  vec3 g;",
    "  g.x  = a0.x  * x0.x  + h.x  * x0.y;",
    "  g.yz = a0.yz * x12.xz + h.yz * x12.yw;",
    "  return 130.0 * dot(m, g);",
    "}"
  ].join("\n");

})(
  this.Blotter, this._
);
